LONDON (Reuters Health) - Most men treated with vardenafil (Levitra) for erectile dysfunction experienced markedly improved erections, according to results of phase III trials presented Monday at the World Congress of the International Society for Sexual and Impotence Research in Montreal.

One trial involved 805 men with erectile dysfunction who received vardenafil 5 mg, 10 mg or 20 mg or placebo for up to 26 weeks.

Investigators found that men on the 20-mg dose were successful in 74% of their first attempts in penetrating their partner compared with 46% of men on placebo. Those who were successful the first time continued to achieve successful penetration in 91% of subsequent attempts.

"Men want to be confident that the erectile dysfunction drug they are taking works the first time and time after time," said Dr. Luc Valiquette, Professor of Urology at the Hospital Saint-Luc du CHUM in Montreal, in a statement by Bayer and GlaxoSmithKline.

"I've seen frustration in some of my patients because the current treatments do not consistently work, and their efficacy may diminish over time. This reinforces the need for new oral therapies that are effective, consistent and safe."

The companies said that a 6-month open-label study showed that 81% of men with erectile dysfunction reported improved erections.

In another study, the first of its kind to assess the effect of a phosphodiesterase inhibitor on erectile function and depressive symptoms among men with erectile dysfunction following prostate cancer surgery, men taking vardenafil were more likely to report improved erections and fewer depressive symptoms than men taking placebo.

In this phase III clinical trial, 440 men between 44 and 77 years old with erectile dysfunction were randomly assigned to placebo or vardenafil for 12 weeks.

After 12 weeks, of the patients who had undergone bilateral nerve-sparing prostatectomy, up to 71% treated with vardenafil 20 mg reported improvement in erections versus 12% of men taking placebo.

A significant decrease in depressive symptoms was observed among a small subset of depressive prostatectomy patients taking vardenafil.

"Men who suffer from erectile dysfunction following prostatectomy are among the most difficult to treat," said Dr. Gerald Brock, lead study investigator and Associate Professor at St. Joseph's Health Centre in London, Ontario, Canada. "The finding that vardenafil significantly improved erectile function in our study patients is important because more than two thirds of these men had severe ED," he added.

In all the studies, drug-related adverse events were generally mild to moderate in intensity, with the most frequent adverse events being headache, flushing and rhinitis, the companies said.

Vardenafil has been filed with regulators in all major markets. But while US regulators approved it in principle 2 months ago, they asked for new studies that will delay its launch until next year.

Copyright © 2003 Reuters Limited. All rights reserved. Republication or redistribution of Reuters Limited content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters Limited. Reuters Limited shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.